1. Field of the Invention
The invention relates to a combination temperature sensor and bleed valve for an automobile cooling system.
2. Description of Related Art
In an automobile cooling system, it is well known to provide a sensor for detecting the temperature of the coolant and transmitting the detected temperature to an operator-read temperature gauge and to an engine control system. A known practice is to provide a sensor with an externally threaded body that is received by an internally threaded aperture in the cooling system, often in a radiator, in a sealed fashion to prevent leaks. More recent practice is to have the sensor mounted in a component associated with the engine block or intake manifold. This component is often molded of a plastic or composite material. This has necessitated incorporating a metallic insert into the molded plastic or composite, as the composite generally lacks the shear strength for directly molding the threads. The metallic insert has also therefore been known to break loose from the plastic molding when subjected to excessive shear. The process of adding the metallic inserts to the plastic molding also adds to the time and cost of manufacture of the molding.
Coolant sensors are also known that slide into a smooth opening and have an external seal, such as an o-ring, for sealing the opening against coolant leaks. Such a coolant sensor is generally held in the smooth opening by a retainer such as a “horseshoe” clip engaging a slot in the surface of the plastic molding.
A means of releasing trapped air is another well-known and necessary component in an automobile cooling system. The radiator can provide a high point for releasing trapped air, but is seldom the high point for the entire cooling system. Portions of the cooling system will trap air that cannot escape through the radiator, which necessitates installation of a bleed valve at an additional high point. A common practice has been to use a known brake bleeder valve. This threaded attachment requires another metallic insert in the plastic or composite molding, subject to the same limitations in strength and time of fabrication previously discussed. This need for an additional fitting on the plastic molding also increases the size and the cost of the molding.
It would be advantageous to improve the reliability of the coolant sensor and bleed valve installations in these composite moldings, preferably eliminating the need for the extra time, cost and space necessary for the separate bleed valve.